Sexual compatibility between eight Nolana L.f. (Solanaceae) species from Peru and Chile

Abstract

Artificial hybridizations (self- intra- and interspecific) were performed within and between eight species of Nolana (N. adansonii, N. aticoana, N. elegans, N. humifusa, N. ivaniana, N. laxa, N. plicata and N. rupicola). Plant material originated from three fog oases (“lomas”) locations in the Peruvian desert in Peru and two “lomas” locations in the Atacama desert in Chile. Self-pollinations and all possible crosses, including reciprocals, were made between three and five accessions of each species. Crosses were made in replicates of five (or ten in self-pollinations), totaling 310 self-pollinations, 480 intraspecific pollinations, and 2535 interspecific pollinations. Species were generally self-incompatible, with only one accession of N. adansonii and one accession of N. ivaniana exhibiting limited self-fertility as measured by fruit set. Intraspecific compatibility appears to be high with most crosses resulting in greater than 80 % fruit set. Success of interspecific hybridization was initially analyzed based on fruit set, mericarps per fruit and mericarp size, and confirmed by seed counts through X-ray analyses of mericarps, and seed germination. Differences in all these factors were found within seed parent species in response to hybridization with different pollen parent species. Reduction in interspecific fertility was generally seen as lower fruiting success and smaller mericarp size when compared to intraspecific hybridization, while the number of mericarps per fruit remained constant. Seed set was estimated by X-ray analysis of mericarps, revealing differences in seed counts between crosses. Mericarps were sown producing hybrid seedlings from 22 unidirectional species pairs. Previous to these studies, sexual compatibility was known to exist only between N. paradoxa and four other species. The results of these studies are a significant contribution to the current knowledge of sexual compatibility within Nolana and are important for future breeding efforts.